974-P: Beyond Carbohydrate Counting (CC)

Abstract

CC is central to diabetes self-management in patients on insulin. Measuring devices, reference materials, and time are required. Continuous glucose monitoring (CGM) is increasingly available to insulin requiring diabetics: a rich data set that can be used to assess glucose appearance (Ra), disposal (Rd), and insulin need beyond CC. Fat and protein also contribute the height and duration of the glucose concentration curve. This is not accounted for with CC. Most patient's base insulin doses on previous meal experience and CGM directional arrows and not CC. CGM provides a means for individualizing insulin management quantitatively beyond premeal CC. Calculations: Data: CGM meal related glucose concentration vs. time curve, Kg body weight to calculate Volume of distribution (Vd). Glucose clearance [CL = (1/time)*Vd)]. (a)=Vd*Pkglucose*e*conversion factor. Conversion factor (CF = 1.12) converts blood glucose to plasma or interstitial fluid glucose (ISF glucose). Meal/insulin taken can be expressed as glucose appearance (a)/insulin or glucose clearance/insulin taken. (a) and CL make it possible to calculate a true area under the curve which differs with the timing and amount of insulin before the meal. Example: Weight 80.1 kg; Vd = 135 dL, time 340 minutes. Baseline glucose (BL) = 71.5 mg/dL. Glucose Peak (Pk) = 159 mg/dL. Insulin taken: 13 units. CL = 43mL/min. Depending on the time insulin is taken before the studied meal: (a) = 159 mg/dL*e*Vd or (a) = (159 mg/dL*e-BL/e) or (a) = ((159 mg/dL*e) - BL)*Vd. CL/insulin and (a)/insulin. In this case: CL = 43 mL/min/13 units; (a) = 48.7 g/13 units. Meal by references: 46.0 g CHO. Conclusion: This methodology marries pharmacokinetics with diet/insulin responses and goes beyond problematic CC in quantitating glucose appearance and disposal. The calculations determine post-hepatic glucose appearance and disposal. If available meal glucose is known, hepatic glycogen storage can be estimated also. Calculations can be performed using a ruler, cell phone calculator, and CGM glucose curves. Disclosure J.S. Melish: None.